Arctic Predators Hit Hard by Climate Change

Much has already been said of the potentially large-scale physical and biological effects of climate change on individual ecosystems and states as a whole. Less emphasis has been placed on the study of the effect of global warming on specific species, particularly those whose role in the food chain makes their presence essential to the stability of the ecosystem.

A new project headed by Nigel Yoccoz in collaboration with Rolf Anker Ims, both from the University of TromsÃ¸, will seek to understand the reduction in the population of several Arctic predators as a consequence of climate change. They are particularly interested in studying the arctic fox, a key predator that was recently placed on the endangered species list.Because the fox's habitat in the Arctic tundra is particularly vulnerable to the effects of global warming, Yoccoz and Ims believe that it and other similar predators can serve as indicators of what is happening in the ecosystem as a whole. "Research on ecosystems is complex as it deals with dynamics in all living species in interaction with each other and with non-living aspects of their environment," says Professor Ims. "One of the objectives of this project is to examine whether it's possible to create a simplification by using the predator community as an ecosystem indicator."

In a typical food chain, predators such as the Arctic fox sit at the very top of several levels that encompass species like the snowy owl and rough-legged buzzard. Since predators are vulnerable to even the slightest change in the prey population, they often serve as effective proxies for the health of the ecosystem as whole.

"The Arctic fox is being utilised as the key species in this research project because it is found through the tundra area, as well as being in clear decline in many areas," says Professor Ims. "The Arctic fox population is on the decline in particular in the southern part of the tundra and in the Scandinavian high mountains. It is in danger of disappearing from Norway."

Although Arctic foxes once numbered in the thousands in Norwegian mountain and northern coastal areas, their population since then has plummeted and it now stands at just 100. Yoccoz and Ims have discovered that the number of new Arctic fox offspring born into a litter correlates directly with the number of Norway lemmings present in the ecosystem. Indeed, the lemming is also a key species in the Arctic tundra, one whose presence or lack thereof can have a drastic effect on the entire food chain from vegetation to large predators.

And, unfortunately, it appears as though global warming is exerting a pernicious effect on lemmings as well. "It appears that the good years for lemmings are becoming rarer with global warming," says Professor Ims, adding. "This can result in the Arctic fox and snowy owl, two of the most characteristic species in the Arctic, disappearing from the tundra."

The scientists hope to gain a better understanding of the Arctic ecosystem as a whole through their study, critical knowledge that will allow them to find and create effective ecological approaches to managing the problems caused by climate change.

"Rapid climate change can result in the world losing its biodiversity," says Professor Ims. "The Arctic tundra can be particularly vulnerable. There is a relatively narrow strip between the northern forest and the Arctic sea areas. If the scenarios for climate change are correct, the forest can in time stretch right out to the coast and completely consume this unique ecosystem."